Expert: Jayendra Upadhye - 5/14/2007

Question
What is the average distance from earth to the greenhouse gases? What is the distance from the center of the earth to the greenhouse gases? And what is the surface area sphere generated of the greenhouse gases?

Answer
Goodness katie!
what has distance got to do with greenhouse gases?
Likewise, what has distance from the earth's center got to do with these gases?
And surface area of sphere ....?
Katie i sincerely hope you are not making a complete fool of poor old me!!

The greenhouse gas Carbon-dioxide resides all over the atmosphere, but is more densely "available" in the lower atmosphere!

Likewise methane / nitrous oxide / and plain old water vapour too are greenhouse gas components.

Any gas that is opaque to infra-red is a greenhouse gas.
Because it is transparent to incoming ultraviolet thru visible spectrum of light, but is opaque to reflected "thermal infrared emission", thus effectively trapping energy inside it. [meaning in its own volume as well as the earth's surface directly.

Any medium opaque / translucent to light absorbs light energy in its "body". In case of the earth,
1 - direct non-infrared sunlight heats the surface,
2 - the heated surface emits secondary infrared .
3 - the overlying greenhouse gases trap this thermal infrared and increase the temperature of the gas envelop of the earth by dissipating the energy within their own volumes.
4 - This further increases surface temperature, yielding higher infrared flux from the ground and so on.
It is a runaway process.

Like a tank storing water and raising water pressure on its bottom over time, the green house accumulates solar energy over time, increasing "available thermal energy" in the heat capacity of the atmosphere + soil combination.

In arid areas it will vary in comparison with wet areas as water vapor is a green house gas.

The distance you need (for whatever reason would then be the radius of the earth..because the atmosphere in thickness does not matter in comparison with it.) !!

I hope you were NOT referring to the astronomical unit of 93 million miles! Distance from sun does not matter as long as we are not comparing severity of the effect between two planets.

In that scenario, more distant planets could still be warmer if they had greenhouse gases as abundant as on venus!

In that case too the overall area of the radiating sphere (surface area of the earth) would enter calculations.
You see, like a tank that settles in level at the point where inflow equals outflow, The earth's "local temperature" at any point on its surface is function of avearge of net energy input by sun and net energy radiated by earth back (which varies as its surface area).
That is why average temperatures vary from summer to winter.
(as the solar flux varies thanks to the earth's roundness as well as axial tilt, from point to point over its surface).
Even with a straight untilted axis, one would still have winter at the poles, and summer at the equator at any given point of time due to solar flux variation over latitude.

In absolute space in earth's vicinity, the solar constant rules supreme, at 1.4 kilowatt / square meter!! Abundant energy provided we can convert and use it!!

Hope you do not find my answer too irrelevent and disappointing.
Jayen